The overall objectives of this research are to continue studies on the feasibility of and immunologic response to interspecies storage of the heart (xenobanking), to determine if xenobanking results in privileged survival of the heart on retransplantation, and to study the role of polymorphonuclear leukocytes in rejection of skin xenografts. The specific goals set for the current year are to study the role of antibodies in the rejection of goat hearts stored in calves and then retransplanted to unrelated immuno-suppressed and untreated goats; and to continue studies on the fate of rat and mouse skin grafted to skin pedicles raised from the flank of guinea pigs.